In a next generation radio access scheme for which research and development are currently being conducted, it is required to perform communication more efficiently compared with conventional schemes. In the downlink, speed-up and increase of capacity for communication are especially required. Thus, radio access schemes of a multicarrier scheme such as orthogonal frequency division multiplexing (OFDM) are highly expected. On the other hand, the uplink is different from the downlink in that speed-up and large capacity are not so strongly required for the uplink as the downlink and that transmission power of a mobile station is considerably limited compared with that of the base station and the like. Thus, the multicarrier scheme in which there is a fear that peak to average power ratio (PAPR) becomes large is not a proper scheme for the uplink. Rather, from the viewpoint of suppressing PAPR and increasing coverage of a cell, it is desirable to adopt a single carrier scheme for the uplink.
By the way, in the next generation radio access scheme, wide range of system frequency band is prepared, and it is predicted that mobile stations perform communication using the whole or a part of the band. In view of properly suppressing PAPR in various uplink bands and decreasing effects exerted on adjacent bands, it is necessary to properly perform band limitation (that is also called wave shaping or spectrum shaping).
However, in conventional radio access schemes, the system frequency band is fixed to 5 MHz, for example, and the band limitation scheme is also fixed. If the conventional technique is used for the next generation radio access scheme, there is a fear that system capacity is restricted due to the fact that proper wave shaping is not performed.
By the way, a non-patent document 1, for example, discloses that chip data sequence after code spreading is band-limited to a band of 5 MHz by a raised cosine root Nyquist filter (roll-off factor is 0.22).
[Non-patent document 1] 3GPP, TS25.101, “User Equipment (UE) radio transmission and reception (FDD)”